Eddy current test was employed to detect any change in the homogeneities of the tubes, and to identify any crack-like-defects.
This technique was employed to measure the diametrical dimensions of the tube exterior, and to detect any diametric change in the tube of the reformer furnace. This is the correct starting point for evaluation of the tube creep.
The LEO-Scan inspection system for external tube inspection is mounted on a compressed air driven Tube Crawler System. The crawler contains probes for Eddy Current inspection of the tube wall as well as laser sensors for the outer diameter measurement.
This is a magneto-inductive method with a special coil configuration, which allows very good penetration into the tube wall. All irregularities, e.g. cracks, porosity separations, can be detected from the outside of the tube. Indications can be shown on a display or recorder.
In addition to the crack detecting technique there is an integrated outer tube diameter measurement with a dual axis laser system. Crack Detection and OD measurement are carried out simultaneously and can therefore be correlated with great success via a positioning encoder.